He was taken to a Dallas County jail where he will be charged with murder.

Update at 9:40 p.m., by Tristan Hallman:

Cowherd worked for Luminant as an associate engineer, the company announced in a statement expressing sadness over his slaying.

Cowherd, a Prairie View A&M graduate began "what would have been a long and fruitful career" on Nov. 5, 2012, after working with the Arkansas State Highway and Transportation Department, the company said in the statement. Kim Mireles, Luminant's vice president of environmental services, said in the statement that Cowherd was one of the friendliest members of the staff.

“It is not surprising that Terrell interceded in an altercation to calm the situation," she said. "Terrell exuded leadership qualities at a very young age."

Company officials also offered their thoughts and prayers to Cowherd's family and lauded Dallas police for the quick arrests.

Update, Sunday at 4:22 p.m. -- Melissa Repko reports:

Police have identified the suspect as Julian Terence Martin, Jr., 23.

A family friend recognized Martin as the shirtless man in the video released by police. After police identified Martin as a suspect, he turned himself in at 2 p.m. Sunday.

Police say Martin pulled a knife from his pants pocket and stabbed Cowherd while Brown was beating him.

Martin is being held at Dallas County Jail. Police said his bond has been set at $250,000, and he will be charged with murder.

Police say they have identified the third man described as a person of interest, but are still investigating his role in the stabbing.

Update, Sunday at 2:21 p.m.: Police have arrested another suspect in connection to Saturday's fatal stabbing on Lower Greenville.

Police chief David Brown tweeted WFAA on Sunday afternoon that a suspect was in custody:

@wfaachannel8 we just took this suspect into custody...thanks for your retweets and mentions

Update, 5:05 p.m.: Police released this video of Cowherd and the man they believe stabbed him, taken seconds before the stabbing occurred.

Update, 1:47 p.m.: Police said they have arrested one person and are searching for two more in the investigation into Terrell Evan Cowherd's death.

Twenty-three-year-old Jerry Brown has been charged with murder. Investigators said he restrained Cowherd while another man stabbed him. The stabber is still at large, though police described him as a man in his 20s with a muscular build and tattoos of wings on each of his shoulder blades. He is five feet nine inches tall and weighs about 170 pounds, police said. No name was available.

Police said they are also looking for a third "person of interest" in the case, though it's unclear exactly what role they believe he played in the stabbing. He was described as five feet eight inches tall, between 160 and 180 pounds with gold teeth.

The two men might have left the scene in a white sedan, police said. Investigators will release pictures of the men soon.

Authorities also released more information about the incident. They said Cowherd was hanging out with friends at Club Kush on Lower Greenville when a fight broke out in the street. Cowherd and dozens of other people in club rushed out to watch, many of them shooting the incident on their cell phone cameras.

Cowherd, who works as an engineer, attempted to break up the fight and stepped between the missing suspect and another man. Words were exchanged, Cowherd was restrained and then stabbed several times. He died soon after.

"Mr. Cowherd is a good Samaritan and [was] trying to break the fight up," said Maj. Jeff Cotner of the Dallas Police Department.

Original, 10:30 a.m.: Dallas police are investigating the stabbing a 26-year-old man just before the bars closed Saturday morning in Lower Greenville.

The stabbing happened near the intersection of Greenville Avenue and Sears Street. A police report identified the victim as 26-year-old Dallas resident Terrell Evan Cowherd.

Details of the incident are sketchy, but a witnesses told WFAA-TV (Channel 8) that it started as a fight between two men. The case escalated and one man ended up stabbing another while others were holding the victim back, the witness told the television station.

Cowherd was transported to the Baylor University Medical Center at Dallas.